A kind of method for preparing low silicon Beta zeolites
Technical field
The present invention relates to a kind of synthetic method of Beta zeolites, more particularly to a kind of synthesis of low silica-alumina ratio Beta zeolites
Method, belongs to molecular sieve catalytic material synthesis field.
Background technology
Beta zeolites were synthesized first in 1967 by Mobil companies, due to failing to solve the problems, such as its structure determination for a long time,
So a very long time fails to arouse enough attention.Until its distinctive Three Dimensions Structure is disclosed within 1988,
Beta zeolites are aroused people's interest again.Beta zeolites have good heat and hydrothermal stability, and appropriate is acid and thermally-stabilised
Property and hydrophobicity, and be table in unique macropore high-silica zeolite for having and intersecting twelve-ring channel system, its catalytic process
Reveal the characteristics of hydrocarbon reaction is difficult coking and long service life, hydrocarbons hydrogenation cracking, hydroisomerization, alkane aromatization,
Excellent catalytic performance is shown in terms of alkylation and transalkylation reaction, is highly important catalysis material.
At present, the oxide silicon aluminum ratio of the Beta zeolites of conventional method synthesis is general 20~200, and is readily synthesized;But
Synthesizing Si-Al is wanted than the rich aluminium Beta zeolites less than 20, it is relatively difficult.Rich aluminium Beta zeolites are relatively low due to its silica alumina ratio,
With higher sour density, higher catalytic reaction efficiency can be shown in some catalytic reactions, is a kind of important urge
Change material.
A kind of CN101096275A, synthetic method of rich aluminium Beta zeolites, discloses a kind of synthetic method of Beta zeolites.
Its synthesis step is:1. impregnating silicon source with the aqueous solution containing silicon source or acid solution, stirring is to solidifying, with or without at ammoniacal liquor
Aging is dehydrated after reason, after grinding, is calcined at 600~1400 DEG C, is obtained silicon and aluminum source;2. again by tetraethylammonium cation
Compound and hydrofluoric acid mixing, in normal pressure and under not higher than 130 DEG C or vacuum condition, evaporate part moisture;3. by silicon and aluminum source
In the tetraethyl ammonium hydroxide and hydrofluoric acid mixed solution that add concentration, then obtained reactant mixture is subjected to hydrothermal crystallizing and returned
Receive crystallization product.Although the patent can synthesize the Beta zeolites of low silica-alumina ratio, its building-up process is comparatively laborious.
A kind of CN101096274A, preparation method of rich aluminium Beta zeolites, discloses a kind of synthetic method of Beta zeolites.
Its synthesis step is:1. silicon source and silicon source are prepared into silica-alumina cogels in the presence of hydrolytic reagent, crushed after aging and roasting
It is used as silicon and aluminum source;2. and then silicon and aluminum source is added to the solution being made up of tetraethylammonium cation, ammonium ion, fluorine ion and water
In, crystallization simultaneously reclaims crystallization product and obtains zeolite.Although the patent can synthesize the Beta zeolites of low silica-alumina ratio, volume
Outer use fluorine ion, not only increases cost, and pollution environment.
CN1086791A, directing agent method synthesis Beta zeolites, discloses a kind of synthetic method of Beta zeolites, synthesis
Beta zeolites fall within low silica-alumina ratio zeolite.Being mainly characterized by of the patent synthesizes Beta zeolites using directed agents.It is oriented to
Agent is to be dissolved in aluminium salt in tetraethyl ammonium hydroxide template and sodium hydrate aqueous solution, adds active silica and is led to prepare
To agent, its directed agents formula range is: SiO2/Al2O3=20~120, TEAOH/SiO2=0.2~0.5, Na2O/SiO2=
0.40~0.10, H2O/SiO2=7.5~25, the preparation temperature of directed agents is 15~70 DEG C, and Aging Temperature is 50~150 DEG C, is closed
During into zeolite, added directed agents are 0.5%~10% with the volume ratio of synthesis material mixture.
Although prior art discloses the synthetic method of several low silica-alumina ratio Beta zeolites, relative to high silicon Beta zeolites
Synthetic technology is not also overripened, and its synthesis step is also relatively cumbersome.And low silica-alumina ratio Beta zeolites are because with uniqueness
Catalytic property, is a kind of important catalysis material, therefore the synthetic method of the more advanced rich aluminium Beta zeolites of exploitation just has weight
The realistic meaning wanted.
The content of the invention
In view of the shortcomings of the prior art, the present invention provides a kind of method for preparing low silicon Beta zeolites, invented party's legal system
Standby obtained zeolite has the feature of low silica-alumina ratio, and whole preparation process is simple and easy to apply, is adapted to industrialized production.
The Beta zeolite crystal structures that the present invention is provided are typical BEA structures, without other impurity crystal;Oxide silicon
Aluminum ratio is less than 20;Crystal size is less than 200nm, belongs to little crystal grain zeolite.
The method of the present invention for preparing low silicon Beta zeolites, comprises the following steps:
(1)Aluminum nitrate is calcined 1~5h at 450~700 DEG C, aluminum oxide is obtained;
(2)By inorganic base, silicon source, silicon source, water and template(TEA)According to 1~8Na of mol ratio2O:30~70SiO2:
A12O3:500~1500H2O:15~40TEA ratio mixing, obtains silica-alumina gel, then under the conditions of 0~15 DEG C after stirring
1 ~ 2d of aging;
(3)By step(1)Obtained aluminum oxide and step(2)Obtained silica-alumina gel mixing, then adds Beta zeolites
Crystal seed, is then dried at 80~180 DEG C, until moisture evaporating completely;
(4)Then by step(3)Obtained dry glue loads reactor top, and reactor bottom adds quantitative water, 100
At a temperature of~170 DEG C, 20~120h of crystallization and is dried to obtain beta zeolites at separating, washing.
The present invention is prepared in the method for low silicon Beta zeolites, step(1)Described in sintering temperature be 500~600 DEG C;Roasting
The burning time is 1.5~4h.
The present invention is prepared in the method for low silicon Beta zeolites, step(2)Described in inorganic base be NaOH, KOH, LiOH
One or more;Silicon source is the one or more in sodium aluminate, aluminum sulfate, aluminium chloride, aluminum nitrate;Silicon source can be white carbon
One or more in black, silica gel, Ludox or waterglass;Template is tetraethyl ammonium hydroxide and/or tetraethylammonium bromide.
The present invention is prepared in the method for low silicon Beta zeolites, step(2)Described in inorganic base, silicon source, silicon source, water and mould
The mol ratio of plate agent is 2~7Na2O:35~60SiO2:A12O3:H2O:20~30TEA.
The present invention is prepared in the method for low silicon Beta zeolites, step(3)Described in aluminum oxide and step(2)Described in silicon
The mol ratio in source is 15~1SiO2:A12O3, preferably 10~2SiO2:A12O3。
The present invention is prepared in the method for low silicon Beta zeolites, step(3)Described in Beta zeolite seed crystals addition and step
Suddenly(2)Described in silicon source with SiO2The mass ratio of meter is 0.005~0.07, preferably 0.01~0.05.
The present invention is prepared in the method for low silicon Beta zeolites, step(3)Described in drying process temperature be 100~140
℃
The present invention is prepared in the method for low silicon Beta zeolites, step(4)Middle water and step(2)Described in silicon source rub
You are than being 0.5~5H2O:SiO2, preferably 1~3H2O:SiO2。
The present invention is prepared in the method for low silicon Beta zeolites, step(4)Described in crystallization condition be 110~150 DEG C at,
20~72h of crystallization.
The present invention is prepared in the method for low silicon Beta zeolites, step(4)Described in separation and washing be this area skill
Routine operation known to art personnel.The method that can take filtering is such as separated, washing generally refers to be washed with deionized.Generally
Including separating for several times and washing operation, generally 1~6 time.Drying condition be usually under the conditions of 100~140 DEG C dry 5~
15h。
The Beta zeolites that the present invention is provided may be used as gas, the adsorbent of liquid mixture separation, can also be as urging
The carrier or acidic catalyst component of agent, can be widely applied to petrochemical industry.
Compared with prior art, the method for preparing low silicon Beta zeolites that the present invention is provided has advantages below:
The present invention is prepared in the method for low silicon Beta zeolites, and aluminum nitrate roasting is allowed to be decomposed into a kind of inert oxidation
Aluminium, this special inert alumina can show strong inertia in Beta zeolite crystallization courses of reaction, i.e., relative to step
Suddenly(2)Described in common silicon source can delay participate in zeolite crystallization, can so make Beta zeolite crystallizations reaction be divided into
Two stages, first stage:Step(2)Described in common silicon source first reacted with other raw materials, generate Beta zeolite nucleus;The
Two-stage:Treat step(2)Described in the consumption reaction completely of common silicon source after, add special aluminum oxide and participate in reaction again, and
And can realize and slowly discharge aluminium species, can so ensure whole reaction system silica alumina ratio maintain all the time one compared with
High level, is conducive to the growth of Beta zeolites, and can suppress the generation of impurity crystal, and then can synthesize high-purity
Low silica-alumina ratio Beta zeolites.Operation is simple for the synthetic method that the present invention is provided, and is adapted to industrialized production.Can be in raw material
In the relatively low scope of silica alumina ratio, synthesis obtains low silica-alumina ratio Beta zeolites, and with higher sour density, in some catalytic reactions
With higher catalytic reaction efficiency.
Brief description of the drawings
Fig. 1 is the XRD spectra for the Beta zeolites that embodiment 1 is obtained.
Embodiment
The synthetic method of analcime of the present invention is described in detail below by specific embodiment, but is not limited to
Embodiment.
Embodiment 1
(1)16g aluminum nitrates are placed in high temperature furnace first, 3h is calcined at 500 DEG C.
(2)0.27g NaOH, 0.1g sodium aluminates, the tetraethyl ammonium hydroxides of 30mL 25% is taken to be placed in 50mL distilled water,
Stirring is until all dissolvings, then add 8g white carbons, stir, then the aging 1.5d under the conditions of 10 DEG C.
(3)By step(1)Special aluminum oxide is prepared in step(2)The silica-alumina gel mixing of preparation, adds 0.08g
Beta zeolite seed crystals, then it is placed in 110 DEG C of dry 12h in baking oven.
(4)Then by step(3)Obtained dry glue loads reactor top, and reactor bottom adds 10 mL distilled water, dress
Enter in closed reactor, 140 DEG C of crystallization 48h in baking oven.Resulting product is extremely neutral with water washing is distilled 4 times, 120 DEG C
12h is dried, gained sample number into spectrum CL1, gained sample are as shown in figure 1, be pure beta zeolites, without other impurity.
Embodiment 2
(1)10g aluminum nitrates are placed in high temperature furnace first, 2h is calcined at 600 DEG C.
(2)0.27g potassium hydroxide, 0.3g aluminum nitrates, the tetraethyl ammonium hydroxides of 30mL 25% is taken to be placed in 50mL distilled water,
Stirring is until all dissolvings, then add 8g white carbons, stir, then the aging 2d under the conditions of 8 DEG C.
(3)By step(1)Special aluminum oxide is prepared in step(2)The silica-alumina gel mixing of preparation, adds 0.1g Beta
Zeolite seed crystal, then it is placed in 120 DEG C of dry 12h in baking oven.
(4)Then by step(3)Obtained dry glue loads reactor top, and reactor bottom adds 12 mL distilled water, dress
Enter in closed reactor, 140 DEG C of crystallization 40h in baking oven.Resulting product is extremely neutral with water washing is distilled 4 times, 120 DEG C
12h is dried, gained sample is beta zeolites, and numbering is CL2.
Embodiment 3
(1)12g aluminum nitrates are placed in high temperature furnace first, 2h is calcined at 700 DEG C.
(2)0.3g NaOH, 0.35g aluminum sulfate, the tetraethyl ammonium hydroxides of 30mL 25% is taken to be placed in 50 mL distilled water
In, stirring is until all dissolvings, then add 8.5g silica gel, stir, then the aging 1.5d under the conditions of 5 DEG C.
(3)By step(1)Special aluminum oxide is prepared in step(2)The silica-alumina gel mixing of preparation, adds 0.13g
Beta zeolite seed crystals, then it is placed in 130 DEG C of dry 12h in baking oven.
(4)Then by step(3)Obtained dry glue loads reactor top, and reactor bottom adds 15 mL distilled water, dress
Enter in closed reactor, 150 DEG C of crystallization 50h in baking oven.Resulting product is extremely neutral with water washing is distilled 4 times, 120 DEG C
12h is dried, gained sample is beta zeolites, and numbering is CL3.
Embodiment 4
(1)17g aluminum nitrates are placed in high temperature furnace first, 3.5h is calcined at 560 DEG C.
(2)0.27g NaOH, 0.1g sodium aluminates, 30g tetraethylammonium bromides is taken to be placed in 60mL distilled water, stirring is straight
To whole dissolvings, then 8g white carbons are added, stirred, then the aging 1d under the conditions of 0 DEG C.
(3)By step(1)Special aluminum oxide is prepared in step(2)The silica-alumina gel mixing of preparation, adds 0.08g
Beta zeolite seed crystals, then it is placed in 110 DEG C of dry 12h in baking oven.
(4)Then by step(3)Obtained dry glue loads reactor top, and reactor bottom adds 8 mL distilled water, dress
Enter in closed reactor, 125 DEG C of crystallization 35h in baking oven.Resulting product is extremely neutral with water washing is distilled 4 times, 120 DEG C
12h is dried, gained sample is beta zeolites, and numbering is CL4.
Comparative example 1
0.27 g NaOH, 0.1 g sodium aluminates, the tetraethyl ammonium hydroxides of 16g aluminum nitrates 30mL 25% is taken to be placed in 50 mL
In distilled water, stirring adds 0.08g Beta zeolite seed crystals, stirred up to all dissolvings, then add 8g white carbons,
The aging 1.5d under the conditions of 10 DEG C.It is reloaded into closed reactor, 140 DEG C of crystallization 48h in baking oven.Resulting product is used
Water washing is distilled 4 times to neutral, 120 DEG C of dry 12h, gained sample number into spectrum CL5, and gained sample is P type zeolite, without beta boilings
Stone.
Comparative example 2
0.27 g NaOH, 0.1 g sodium aluminates, the tetraethyl ammonium hydroxides of 16g aluminum nitrates 30mL 25% is taken to be placed in 50 mL
In distilled water, stirring is until all dissolvings.8 g white carbons are added again and add 0.08g Beta zeolite seed crystals, stirring is equal
It is even, the aging 1.5d under the conditions of 10 DEG C.110 DEG C of dry 12h in baking oven are placed in again.Then dry glue is loaded into reactor top, instead
Answer device bottom to add 10 mL distilled water, be fitted into closed reactor, 140 DEG C of crystallization 48h in baking oven.By resulting product
With water washing is distilled 4 times to neutrality, 120 DEG C of dry 12h, gained sample number into spectrum CL6, gained sample are P type zeolite, without beta
Zeolite.
Comparative example 3
(1)16g aluminum nitrates are placed in high temperature furnace first, 3h is calcined at 900 DEG C.
(2)0.27 g NaOH, 0.1 g sodium aluminates, the tetraethyl ammonium hydroxides of 30mL 25% is taken to be placed in 50 mL distilled water
In, stirring is until all dissolvings.8 g white carbons are added again, are stirred, then the aging 1.5d under the conditions of 10 DEG C.
(3)By step(1)Special aluminum oxide is prepared in step(2)The silica-alumina gel mixing of preparation, adds 0.08g
Beta zeolite seed crystals, then it is placed in 110 DEG C of dry 12h in baking oven.
(4)Then by step(3)Obtained dry glue loads reactor top, and reactor bottom adds 10 mL distilled water, dress
Enter in closed reactor, 140 DEG C of crystallization 48h in baking oven.Resulting product is extremely neutral with water washing is distilled 4 times, 120 DEG C
12h, gained sample number into spectrum CL7 are dried, is a kind of crystalline alumina, it is impossible to synthesize Beta zeolites.
Comparative example 4
(1)16g aluminum nitrates are dissolved in 200mL distilled water first, 200mL then is added dropwise under stirring
0.3mol/L sal volatile, obtains white gels;Gel is placed at 120 DEG C again and dries 12h, then in 750 DEG C of roastings
3h, obtains aluminum oxide.
(2)0.27g NaOH, 0.1g sodium aluminates, the tetraethyl ammonium hydroxides of 30mL 25% is taken to be placed in 50mL distilled water,
Stirring is until all dissolvings, then add 8g white carbons, stir, then the aging 1.5d under the conditions of 10 DEG C.
(3)By step(1)Special aluminum oxide is prepared in step(2)The silica-alumina gel mixing of preparation, adds 0.08g
Beta zeolite seed crystals, then it is placed in 110 DEG C of dry 12h in baking oven.
(4)Then by step(3)Obtained dry glue loads reactor top, and reactor bottom adds 10 mL distilled water, dress
Enter in closed reactor, 140 DEG C of crystallization 48h in baking oven.Resulting product is extremely neutral with water washing is distilled 4 times, 120 DEG C
12h, gained sample number into spectrum CL8 are dried, gained sample is gama-alumina, it is impossible to synthesize Beta zeolites.
The crystalline phase property of the embodiment of table 1 and comparative example products therefrom
Note:The relative crystallinity that table 1 is given is using CL1 crystallinity as reference.